This study aims to assess the feasibility of fuel-reforming-assisted hydrocarbon selective catalytic reduction (HC-SCR) over 2 wt % Ag/Al 2O3 catalyst. For this purpose, the effects of reduction agents and the presence of hydrogen on NOx reduction over silver catalyst were tested, and, after catalytic partial oxidation (CPOx) reforming performances were studied, the DeNOx performance of reformate-assisted HC-SCR was investigated. Although normal heptane/octane/ dodecane showed better NOx reduction rates at 300 and 350 °C than the other C2-C4 range hydrocarbons, the performances were still unpractical at the temperature range similar to actual diesel exhaust. To enhance the low temperature activity of the Ag/Al2O3 catalyst, CPOx reforming was tested and applied in the SCR system. By the addition of CPOx products to the HC-SCR reactor, NOx reduction performance was increased to a great extent especially in the low temperature range between 200 and 400 °C. For the reductant condition of C/N = 6 + CPOx/N = 6 without water, about 52.5% of NOx reduction was recorded over C3H6-SCR at 300 °C, whereas nearly zero DeNO x efficiency was measured when only C3H6 was present in the reactants. Also, it was found that C/N = 6 + CPOx/N = 6 showed the better NOx reduction efficiency than C/N = 3 + CPOx/N = 9. Together with the hydrogen model gas tests results, it implies that there is an optimum hydrogen to hydrocarbon ratio in terms of low-temperature activity enhancement assuming that the total amount of fuel used in CPOx-assisted HC-SCR is the same. In addition, inhibition effect by water was reduced to an extent by CPOx products. C3H6-SCR was deactivated so seriously that no NOx conversions were measured at 300 and 400 °C in the presence of water vapor. However, through the addition of CPOx products to the C3H6-SCR reactants, NOx reduction was increased to 20% at 300 °C and 25% at 400 °C.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering